The present invention relates to a positional data input device for a computer and, in particular, to a cordless graphics input device which when used in conjunction with a photo-optic detector and processor, determines the Cartesian coordinate location of the cordless device.
Heretofore, a variety of computer data entry devices have existed. For example, light pens, joy sticks track balls, and capacitively interconnected screens and pens, are known in the art and which permit an operator to couple positional or coordinate related data to a computer. Such devices, however, are dependent upon an interconnected cord or electrical connection between the hand held position indicating device and the reference plane. Examples of some of such devices can be found upon reference to U.S. Pat. Nos. 3,886,311; 3,857,002; 3,790,709; and 3,626,483.
Digital cursor positioning devices of the type colloquially referred to as digital "mice", on the other hand, are of a recent innovation to computer display systems. Generally, they comprise a hand-held device which, when moved about a specially constructed pad, generates signals that are fed through a cord to control the positioning of a cursor on a CRT display screen. Thus, upon calibrating the mouse or graphics input device (GID) to the surface upon which it rests, the GID, via its on-board circuitry, sends positional data to the computer which then appropriately responds in the manner dependent upon its programmed mode of operation relative to the GID's movement. Manually generated commands to the computer may also be determined by one or more switches disposed on the GID, the state of the switches being sensed by the associated computer.
The prior art computer graphics input devices thus require a direct electrical connection to the computer by a cord. In addition certain types of the prior art GID's depend upon movement upon a special surface, such as a membrane switch array or a printed circuit grid. The necessities of such an interconnecting cord and prepared surface, however, place undue restraints on the use of the GID. In particular, failure to maintain physical contact between the GID and special surface may result in the loss of calibration, if the GID is lifted therefrom. Also, the cord tying the GID to the computer does not provide for free and easy movement, since it trails behind and can get in the way.
While another type of GID has been developed with a housing having a "track-ball" on its undersurface that cooperates with rotary switches to provide positional data, the housing must be held in a predetermined orientation or otherwise the resulting cursor movement will be at an angle with respect to a X-Y coordinate system. Thus, this type of device oftentimes produces operator fatigue.
It is, accordingly, a primary object of the present invention to provide a computer graphics input device that is not mechanically attached to the computer and which does not require continuous operation upon a special surface or in a peculiar orientation. The cordless graphics input device of the present invention may therefore be moved about upon any convenient planar surface relative to an associated stationary, computer coupled detector module. Thus, the GID may be moved at will, independent of any cords, provided a resonably flat surface is available for supporting the detector module and movable GID. Also, the present GID need not be held in any special way to avoid diagonal cursor movement on the display screen.
In lieu of a direct electrical interconnection to the computer via a cable, the present invention, utilizes a photo-optic system wherein a freely movable light source may be moved relative to a stationary detector module (containing appropriate detecting and processing devices) whereby coordinate related position data is generated for use by the computer.
In particular, the present invention comprises a digital, hand-held mouse in which a pulsatile point light source is appropriately generated and transmitted omnidirectionally. A fraction of the light is allowed to pass through spaced-apart, verticle slits and impinge upon a pair of concave sensors in the detector modules which have appropriately patterned areas thereon for creating positionally sensitive, weighted analog signals. The analog signals are, in turn, in a real time fashion, converted to a digital format which is acted upon by the associated computer to perform functions which depend upon the computer's operating software and the state of manual switch contacts selected at the mouse.
The above-mentioned objects, advantages and distinctions of the present invention, as well as various others will, however, become more apparent upon reference to the following description thereof relative to the following drawings. Before referring thereto, however, it is to be recognized that the following description is made with respect to the presently preferred embodiment only and, accordingly, various modifications may be made thereto without departing from the spirit and scope of the invention. Some of such changes will be mentioned hereinafter, but it is to be recognized that still others may be suggested to those of skill in the art.